1. Field of the Invention
The present invention relates to an apparatus for and a method of controlling a solenoid-operated valve device for use as an intake or exhaust valve device in an internal combustion engine.
2. Description of the Related Art
There have heretofore been known solenoid-operated valve devices for use as intake or exhaust valves device in internal combustion engines. The basic structure of a conventional solenoid-operated valve device of the type described is shown in FIG. 1 of the accompanying drawings.
FIG. 1 illustrates a solenoid-operated valve device for use as an intake or exhaust valve device in an internal combustion engine. As shown in FIG. 1, the solenoid-operated valve device has a valve head 3 mounted on one end of a shank 3a and a plate-like armature 4 made of a magnetic material such as iron or the like which is mounted on the other end of the shank 3a. The valve head 3 serves to selectively open and close a port 2 as an intake port or an exhaust port (hereinafter referred to as xe2x80x9cintake/exhaust port 2xe2x80x9d) of a combustion chamber 1 of each of the cylinders of an internal combustion engine. The valve head 3 is vertically reciprocally movable, together with the armature 4 along the axis of the shank 3a, between a closed position in which it closes the intake/exhaust port 2 and an open position in which it fully opens the intake/exhaust port 2.
Another solenoid-operated valve device also has a drive rod (not shown) held in concentric contact with the upper end of a valve stem and movable in unison with the valve stem, with an armature being mounted on the drive rod. In this solenoid-operated valve device, the valve stem and the drive rod jointly correspond to the shank 3a shown in FIG. 1.
Electromagnets 5, 6 having respective solenoids 5a, 6a housed therein are disposed above and below the armature 4 in confronting relation to each other. When the solenoid 5a is energized, the electromagnet 5 serves as a valve closing electromagnet which moves the armature 4 upwardly together with the valve head 3 and attracts the armature 4 under electromagnetic forces, thereby moving the valve head 3 into the closed position. When the solenoid 6a is energized, the electromagnet 6 serves as a valve opening electromagnet which moves the armature 4 downwardly together with the valve head 3 and attracts the armature 4 under electromagnetic forces, thereby moving the valve head 3 into the open position.
A spring 7 for urging the armature 4 and the valve head 3 in the direction to open the valve head 3, i.e., in the downward direction, is disposed above the armature 4, and a spring 8 for urging the armature 4 and the valve head 3 in the direction to close the valve head 3, i.e., in the upward direction, is disposed beneath the armature 4. When the electromagnets 5, 6 are de-energized, the valve head 3 is kept in a neutral position shown as the solid-line position in FIG. 1 between the closed position and the open position under the biasing forces of the springs 7, 8 which are held in equilibrium. Thus, the springs 7, 8 jointly function as a biasing means for urging the valve head 3 in the neutral position.
With the above solenoid-operated valve device, it is necessary to determine a position to which the valve head 3 is to move before the solenoid-operated valve device starts operating with the internal combustion engine. To meet such a requirement, before the internal combustion engine starts operating, the valve head 3 is moved to an initial position, which is either the open position or the closed position, from the neutral position in which the valve head 3 is kept when the electromagnets 5, 6 are de-energized. Such a moving process is hereinafter referred to as xe2x80x9cinitial actuating processxe2x80x9d).
The solenoid-operated valve device is controlled in the initial actuating process as disclosed in Japanese laid-open patent publication No. 59-213913 and Japanese laid-open patent publication No. 10-288014, for example.
According to the disclosed control processes, the electromagnets 5, 6 are alternately periodically energized to generate alternate electromagnetic forces which vibrate the valve head 3 and the armature 4. The electromagnets 5, 6 are energized for a period of time which is half the period of the natural frequency (resonant frequency) of the spring-mass system comprising the valve head 3, the shank 3a, the armature 4, and the springs 7, 8, or which becomes closer stepwise from a period of time somewhat longer than half the period to half the period, thus progressively increasing the amplitude of the vibrations of the valve head 3, etc. based on the resonance of the spring-mass system. When the amplitude of the vibrations of the valve head 3, etc. becomes sufficiently large, the alternate energization of the electromagnets 5, 6 is finished, and only the electromagnet 5 or 6 corresponding to the initial position (the open or closed position) of the valve head 3 is continuously energized. The electromagnetic forces generated by the electromagnet 5 or 6 corresponding to the initial position attract the armature 4, seating the valve head 3 in the initial position.
According to Japanese laid-open patent publication No. 59-213913, the arrival of the valve head 3 at the open or closed position due to the alternate energization of the electromagnets 5, 6 is recognized based on a reduction in the current passing through the electromagnet 5 or 6, and the alternate energization of the electromagnets 5, 6 is finished when the arrival of the valve head 3 at the open or closed position is recognized. According to Japanese laid-open patent publication No. 10-288014, when the electromagnets 5, 6 are alternately energized a predetermined number of times, the amplitude of the vibrations of the valve head 3, etc. is regarded as being sufficiently large, and the alternate energization of the electromagnets 5, 6 is finished.
According to the disclosed arrangements, since the resonance of the spring-mass system is utilized, the initial actuating process may be performed with a smaller current supplied to the electromagnets 5, 6 than if only the electromagnet 5 or 6 corresponding to the initial position were continuously energized to move the valve head 3 to the initial position under electromagnetic forces generated by the electromagnet 5 or 6.
However, the disclosed processes have suffered the following drawbacks:
When the electromagnets 5, 6 are alternately energized in the initial actuating process, one of the electromagnets is de-energized and at the same time the other electromagnet is energized, and hence either one of the electromagnets is energized at all times (see FIGS. 2 and 3 of Japanese laid-open patent publication No. 59-213913 and FIG. 2 of Japanese laid-open patent publication No. 10-288014).
When the valve opening electromagnet 6, for example, is de-energized and the valve closing electromagnet 5 starts being energized, the armature 4 is spaced relatively widely from the valve closing electromagnet 5, and the electromagnetic forces of the valve closing electromagnet 5 do not well act on the armature 4. In this state, the armature 4 can move toward the valve closing electromagnet 5 under the bias of the springs 7, 8. This also holds when valve closing electromagnet 5 is de-energized and the valve opening electromagnet 6 starts being energized.
Therefore, when the electromagnets 5, 6 are alternately energized, supplied currents are often wasted in certain intervals as they do not contribute to the vibration of the valve head 3, etc., resulting in an excessive consumption of electric energy in the initial actuating process.
According to Japanese laid-open patent publication No. 10-288014, the alternate energization of the electromagnets 5, 6 is finished when they have been alternately energized a certain number of times. In view of variations of the properties of the springs 7, 8, variations of the friction of various parts at the time the valve head 3 is moved, or time-dependent changes thereof, the number of times that the electromagnets 5, 6 are alternately energized generally needs to be set to a relatively large value in order to seat the valve head 3 reliably after the alternate energization of the electromagnets 5, 6 is finished. Therefore, even when the valve head 3 vibrating due to the alternate energization fully reaches the open and closed positions, the electromagnets 5, 6 may remain continuously energized alternately. In this case, impact sounds are produced such as when the armature 4 hits the electromagnets 5, 6, generating noise, and the electromagnets 5, 6 may be alternately energized for an unnecessary long period of time, causing an unnecessary consumption of electric energy.
According to Japanese laid-open patent publication No. 59-213913, since the alternate energization of the electromagnets 5, 6 is finished when the valve head 3 reaches the initial position (the open or closed position), the impact sounds produced such as when the armature 4 hits the electromagnets 5, 6 are relatively large when the valve head 3 reaches the initial position.
It is therefore an object of the present invention to provide an apparatus for and a method of controlling a solenoid-operated valve device to reduce a consumption of electric energy by an electromagnet in an initial actuating process for moving a valve head from a neutral position to an initial position (an open or closed position).
Another object of the present invention is to provide an apparatus for and a method of controlling a solenoid-operated valve device to perform an initial actuating process efficiently and smoothly and prevent noise such as impact sounds from being produced when a valve head is seated, without alternately energizing a valve opening electromagnet and a valve closing electromagnet for an unnecessary long period of time.
Still another object of the present invention is to provide a recording medium which stores a control program for controlling a solenoid-operated valve device with a computer.
To achieve the above objects, there are provided an apparatus for and a method of controlling a solenoid-operated valve device having a valve head movable between an open position to open a fluid passage and a closed position to close the fluid passage, an armature of a magnetic material movable in unison with the valve head, a valve opening electromagnet energizable for generating electromagnetic forces to attract the armature in a direction to move the valve head toward the open position, a valve closing electromagnet energizable for generating electromagnetic forces to attract the armature in a direction to move the valve head toward the closed position, and biasing means for biasing the valve head into a neutral position between the open position and the closed position. An alternate energization process is performed to alternately energize the valve opening electromagnet and the valve closing electromagnet periodically to cause the valve opening electromagnet and the valve closing electromagnet to generate electromagnetic forces alternately to vibrate the valve head together with the armature with an increasing amplitude when the valve head is moved from the neutral position in which the valve head is kept by the biasing means to an initial position which is either one of the open position and the closed position.
According to the present invention, there is also provided a computer-readable recording medium storing a control program for enabling a computer to perform the above alternate energization process.
With the above apparatus and method, in the above alternate energization process, one of the valve opening electromagnet and the valve closing electromagnet is de-energized and thereafter the other of the valve opening electromagnet and the valve closing electromagnet is energized with a delay from the time to de-energize said one of the valve opening electromagnet and the valve closing electromagnet. The recording medium stores the program for enabling the computer to perform the above alternate energization process as the control program for the solenoid-operated valve device.
In the alternate energization process for alternately energizing the valve opening electromagnet and the valve closing electromagnet to vibrate the valve head together with the armature, one of the electromagnets is de-energized at a time and the other electromagnet starts being energized with a delay from the time at which said one of the electromagnets is de-energized. Therefore, immediately after said one of the electromagnets is de-energized (before the other electromagnet starts being energized), the armature moves in unison with the valve head toward the other electromagnet under the bias of the biasing means. When the armature has moved to a certain position closer to the other electromagnet under the bias of the biasing means, the other electromagnet starts to be energized. With the recording medium according to the present invention, the above energization of the electromagnet is performed under the control of the computer.
After said one of the electromagnets is de-energized, while the armature can move smoothly toward the other electromagnet under the bias of the biasing means, both of the electromagnets remain de-energized. When the armature moves to a certain position close to the other electromagnet and the electromagnetic forces from the other electromagnet can effectively act on the armature, the other electromagnet starts being energized.
As a result, in the alternate energization process for moving the valve head from a neutral position to the initial position (the open position or the closed position), the valve head can smoothly be vibrated as desired, and any wasteful energization of the electromagnets is avoided to reduce the consumption of electric energy by the electromagnets.
With the above apparatus and method, in the above alternate energization process, one of the valve opening electromagnet and the valve closing electromagnet is de-energized and, after elapse of a predetermined time, the other of the valve opening electromagnet and the valve closing electromagnet starts to be energized. With the recording medium according to the present invention, the control program stored therein is arranged to energize the electromagnet in the above fashion.
Therefore, the time to start energizing the other electromagnet after said one of the electromagnets is de-energized can easily be delayed. The predetermined time which determines the time to start energizing the other electromagnet should preferably be established such that after said one of the electromagnets is de-energized, the valve head starts moving in a direction opposite to the direction in which it is attracted by said one electromagnet, under the bias of the biasing means, and the other electromagnet starts being energized while the valve head is moving toward the neutral position. The predetermined time should preferably be established such that the sum of the time in which said one electromagnet is energized and the predetermined time is about half the period of the natural frequency of a system comprising the valve head, the armature, the biasing means, etc., i.e., a spring-mass system.
According to another aspect of the control apparatus, the solenoid-operated valve device has a displacement sensor for generating an output signal depending on the position to which the valve head is moved, and one of the valve opening electromagnet and the valve closing electromagnet is de-energized and thereafter the other of the valve opening electromagnet and the valve closing electromagnet starts to be energized from the time when the position to which the valve head is moved, represented by the output signal from the displacement sensor (the detected position to which the valve head is moved), has reached a first displaced position between the open position and the closed position in the alternate energization process.
According to another aspect of the control method, the method has the step of sequentially detecting the position to which the valve head is moved based on an output signal from a displacement sensor, which is provided in the solenoid-operated valve device to detect the position to which the valve head is moved, at least after the alternate energization process has been started, and one of the valve opening electromagnet and the valve closing electromagnet is de-energized and thereafter the other of the valve opening electromagnet and the valve closing electromagnet starts to be energized from the time when the detected position to which the valve head is moved has reached a first displaced position between the open position and the closed position in the alternate energization process.
According to another aspect of the recording medium, the computer is capable of detecting the position to which the valve head is moved based on an output signal from a displacement sensor, which is provided in the solenoid-operated valve device to detect the position to which the valve head is moved, and the control program is arranged to de-energize one of the valve opening electromagnet and the valve closing electromagnet and thereafter start to energize the other of the valve opening electromagnet and the valve closing electromagnet from the time when the detected position to which the valve head is moved has reached a first displaced position between the open position and the closed position in the alternate energization process.
After said one electromagnet is de-energized, the other electromagnet starts to be energized from the time when the actual position to which the valve head is moved as detected by the displacement sensor reaches the first displaced position under the bias of the biasing means and is confirmed as having moved a certain extent closely to one of the open and closed positions which is attracted by the other electromagnet. Therefore, the other electromagnet starts to be energized at a suitable delay time to smoothly vibrate the valve head regardless of variations of the properties of the biasing means, variations of the friction of various parts, and time-dependent changes thereof.
The first displaced position may be set to a common displaced position (e.g., a position near the neutral position) when the valve head moves from the open position to the closed position and when the valve head moves from the closed position to the open position in the alternate energization process. Basically, it is preferable to establish the first displaced position differently when the valve head moves from the open position to the closed position and when the valve head moves from the closed position to the open position. Specifically, when the valve head moves from the open position to the closed position, i.e., after the valve opening electromagnet is de-energized, the first displaced position should preferably be slightly closer to the open position than the neutral position, and when the valve head moves from the closed position to the open position, i.e., after the valve closing electromagnet is de-energized, the first displaced position should preferably be slightly closer to the closed position than the neutral position.
A solenoid-operated valve device for use as an intake or exhaust valve device in an internal combustion engine usually has a displacement sensor for generating an output signal depending on the position to which the valve head is moved in order to control operation of the solenoid-operated valve device while the internal combustion engine is operating. Such a solenoid-operated valve device does not need to have a new displacement sensor.
With the above apparatus and method, the alternate energization process is finished when the position to which the valve head is moved, represented by the output signal from the displacement sensor (the detected position to which the valve head is moved), has reached a second displaced position located closer to either one of the open position and the closed position and between the open position and the closed position after the alternate energization process has been started, and, after the alternate energization process is finished, a valve seating process is performed to continuously energize one of the valve opening electromagnet and the valve closing electromagnet which corresponds to the initial position in order to keep the valve head in the initial position. If the solenoid-operated valve device does not have its own displacement sensor, then a displacement sensor for generating an output signal depending on the position to which the valve head is moved is added to the solenoid-operated valve device, and the above alternate energization process and valve seating process is carried out. The control program stored in the recording medium includes a program for enabling the computer to perform the above alternate energization process and valve seating process.
After the alternate energization process has been started, when the position to which the valve head is moved as detected by the displacement sensor has reached a predetermined position (the second displaced position) near the open position or the closed position, i.e., when the amplitude of actual vibrations of the valve head is confirmed as being sufficiently large in the alternate energization process, the alternate energization process is finished, and the valve seating process is initiated. Consequently, the alternate energization process is finished within a minimum time required and then valve seating process is initiated to hold the valve head in the initial position regardless of variations of the properties of the biasing means, variations of the friction of various parts, and time-dependent changes thereof.
As a result, the time in which the alternate energization process is carried out is held to a minimum required, and operation of the solenoid-operated valve device in the alternate energization process and the valve seating process, i.e., the initial actuating process of the solenoid-operated valve device, can efficiently be performed, and the total amount of electric energy consumed by the valve opening electromagnet and the valve closing electromagnet in the alternate energization process can be reduced. By setting the second displaced position to an appropriate position, it is possible to finish the alternate energization process before the valve head whose vibrating amplitude progressively increases in the alternate energization process reaches the open position or the closed position. Accordingly, before the valve head reaches and is held in the initial position in the valve seating process, noise such as impact sounds which would otherwise be caused by the armature hitting the electromagnets is prevented from being produced.
With the apparatus and method according to the present invention which perform the valve seating process after the alternate energization process is finished, the valve seating process is performed by starting to energize the electromagnet corresponding to the initial position under constant voltage control when the position to which the valve head is moved, represented by the output signal from the displacement sensor, has reached a third displaced position located between the open position and the closed position while the valve head is moving toward the initial position after the alternate energization process has been finished, and then energizing the electromagnet corresponding to the initial position under constant current control when the position to which the valve head is moved has reached a fourth displaced position located closer to the initial position than the third displaced position and near the initial position, thus holding the valve head in the initial position. The control program stored in the recording medium is arranged to enable the computer to perform the above valve seating process.
In the valve seating process, when the valve head reaches the third displaced position upon movement toward the initial position, the electromagnet corresponding to the initial position is energized under constant voltage control, or specifically a control process to energize the solenoid thereof to apply a constant voltage to the solenoid. Therefore, as the armature approaches the electromagnet corresponding to the initial position, the current flowing through the electromagnet increases, and the electromagnetic forces generated thereby also increase, making it possible to move the valve head smoothly toward the initial position. When the valve head reaches the fourth displaced position near the initial position, i.e. immediately before the valve head reaches the initial position, the electromagnet corresponding to the initial position is energized under constant current control, or specifically a control process to energize the solenoid thereof to supply a constant current to the solenoid. Therefore, it is possible to seat the valve head smoothly in the initial position while reducing impact sounds caused when the armature hits the electromagnet corresponding to the initial position, and also to keep the valve head stably in the initial position with a relatively small current supplied to the electromagnet corresponding to the initial position.
Specifically, the third displaced position should preferably be set to a position located between the neutral position and the initial position, for example, but closer to the neutral position than the fourth displaced position.